1. Field of Invention
The present invention relates to a weather strip provided along a surrounding part of a door opening of a vehicle and more particularly to a weather strip having a hollow seal portion.
2. Description of the Related Art
Generally, a weather strip is provided along a surrounding part of a door opening of a vehicle, such as an automobile. As shown in FIG. 5, a weather strip 70 includes a trimming portion 72, which has a substantially U-shaped cross section and held by being fitted into a flange 71 formed in a surrounding part of a door opening, and also includes a hollow seal portion 73 provided in such a way as to protrude from the trimming portion 72. When a door is closed, the seal portion 73 is pressure-contacted to an edge portion of the door, so that the space between the door and a body is sealed. Most of or the entirety of the circumference of the weather strip 70 is formed by extrusion molding.
However, when a corner portion of the weather strip 70 is formed corresponding to a corner portion of the surrounding part of the door opening, especially, to a place at which a bending angle is very acute (that is, a place at which the corner portion is bent so that the angle is a smaller acute one), there is a fear of occurrence of drawbacks in that the seal portion 73 is collapsed, and that a double outside line (that is, an outer circumferential line of the seal portion and that of the trimming portion) is formed. Therefore, the following countermeasures are taken. That is, an occurrence of crushing deformation is prevented by, for example, inserting a pad into the seal portion 73 (see, for instance, Japanese Utility Model Registration No. 2,604,441). Alternatively, a corner part of the seal portion 73 is cut off and then, this part is remolded by injection molding. Alternatively, all corner portions of the weather strip are molded by injection molding.
However, in the case of utilizing a pad, the pad, that is, an additional separate member is needed. There is a fear of occurrences of drawbacks in that the production cost of a weather strip increases, and that the manufacturing process thereof is complicated. When the cutout parts and the corner portions are remolded, an additional step becomes necessary. Thus, there is a fear of occurrences of similar drawbacks. Moreover, the difference in quality between the extrusion-molding part and the injection-molding part occurs. This may result in deterioration in the appearance of a vehicle. Thus, there is a fear of degradation in the quality of the appearance of the vehicle.
FIG. 6 shows another example of the weather strip 50. As shown in FIG. 6, a weather strip 50 includes a trimming portion 52, which has a substantially U-shaped cross section and held by being fitted into a flange 51 formed in a surrounding part of a door opening, and also includes a hollow seal portion 53 provided in such a way as to protrude from the trimming portion 52. When a door is closed, the seal portion 53 is pressure-contacted with an edge portion of the door, so that the space between the door and a body is sealed.
Usually, the trimming portion 52 requires sufficient stiffness. Thus, the trimming portion 52 is formed of solid rubber (non-foam). The seal portion 53 requires flexibility. Thus, the seal portion 53 is formed of sponge rubber (foam). To prevent the seal portion 53 from being fallen down, projection portions 55 and 56 are formed on a vehicular outer side surface of a vehicular outer side wall part 54 of the trimming portion 52 at a connection portion between the trimming portion 52 and the seal portion 53 in such a way as to extend outwardly therefrom. The seal portion 53 is connected to leading end parts of the projection portions 55, 56. For the purposes of preventing the seal portion 53 from being worn away by the pressure-contact between the seal portion 53 and the door and of enhancing the durability of the seal portion 53, a film layer 57 is provided on an outer surface of each of the seal portion 53 and the projection portion 56 (see, for example, Japanese Utility Model Registration No. 2,584,752).
However, the film layer 57 is relatively thin, so that an outside line due to material differences, such as polish and surface roughness, occurs at a boundary portion (that is, the leading end part of the projection portion 56) between the seal portion 53 made of sponge rubber and the projection portion 56 made of solid rubber. Because of the facts that the seal portion 53 is made of foam, and that the projection portion 56 is made of non-foam, there is a fear that a slight step-like portion is formed between the seal portion 53 and the projection portion 56. Therefore, in the case that such an outside line or a step-like portion is placed on a design surface (for instance, a part that can relatively easily and visually be identified from the outside of a vehicle) of the weather strip 50, there is a fear that deterioration of appearance thereof and degradation in the quality of the appearance thereof occur. After the weather strip 50 is formed, surface treatment is sometimes performed on the surface of the seal portion 53 so as to obscure the outside line and the step-like portion. However, there are fears that the production cost of a weather strip increases, and that the process of manufacturing the weather strip is complicated.
Incidentally, according to the weather strip described in Japanese Utility Model Registration No. 2,584,752, in a boundary portion between a body portion and the film layer, a region, in which the quality of the material is gradually changed, is provided therebetween by tapering off the film layer toward an end part thereof in the vicinity of the boundary portion. However, even when tapering off the film layer toward an end thereof (that is, providing the region in which the quality of the material is gradually changed), it is difficult to eradicate the aforementioned outside line at the end part thereof. Thus, even when this technique is applied thereto and when the seal portion 53 is tapered off toward an end thereof in the boundary portion between the seal portion 53 and the projection portion 56, in the case where the end part (thus, the boundary portion) is placed on the design surface, drawbacks similar to the aforementioned ones may occur owing to the emergence of the outside line and the step-like portion.